Methods of forming insulative elements

ABSTRACT

Methods of forming an insulative element are described, including forming a first metal oxide material having a first dielectric constant, forming a second metal oxide material having a second dielectric constant different from the first, and heating at least portions of the structure to crystallize at least a portion of at least one of the first dielectric material and the second dielectric material. Methods of forming a capacitor are described, including forming a first electrode, forming a dielectric material with a first oxide and a second oxide over the first electrode, and forming a second electrode over the dielectric material. Structures including dielectric materials are also described.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/038,605, filed Mar. 2, 2011, pending, the disclosure of which ishereby incorporated herein in its entirety by this reference.

TECHNICAL FIELD

Embodiments of the present disclosure relate to forming an insulativeelement having a high dielectric constant (k) and a low leakage current.Specific embodiments of the present disclosure relate to forming theinsulative element having a high k and low leakage current from a metaloxide material doped with another, different metal oxide material.

BACKGROUND

Capacitors are the basic energy storage devices in random access memorydevices, such as dynamic random access memory (“DRAM”) devices.Capacitors include two conductors, such as parallel metal or polysiliconplates, which act as electrodes. The electrodes are insulated from eachother by a dielectric material. With the continual shrinkage ofmicroelectronic devices, such as capacitors, the materials traditionallyused in integrated circuit technology are approaching their performancelimits. Silicon dioxide (“SiO₂”) has frequently been used as thedielectric material in capacitors. However, with smaller and smallercapacitor area, SiO₂ cannot be thinned to provide sufficient capacitancewhile maintaining low leakage. This deficiency has lead to a search forimproved dielectric materials. High quality, thin dielectric materialspossessing higher dielectric constants (k) than SiO₂ are of interest tothe semiconductor industry. Examples of materials having dielectricconstants (k) greater than SiO₂ include hafnium oxide (“HfO₂”),zirconium oxide (“ZrO₂”), and strontium titanate (“SrTiO₃”). In general,dielectric materials with a higher dielectric constant also exhibithigher leakage currents. Dielectric materials are typically formed bychemical vapor deposition (“CVD”) or atomic layer deposition (“ALD”).However, CVD is unable to provide good step coverage and filmstoichiometry in high aspect ratio containers. Therefore, CVD is notuseful to fill high aspect ratio containers. While ALD provides goodstep coverage, current CVD and ALD techniques each produce high-kdielectric materials that have high leakage.

To produce a capacitor, a bottom electrode is formed on a semiconductorsubstrate and a dielectric material is deposited over the bottomelectrode. The bottom electrode and the dielectric material areannealed, and a top electrode is formed over the dielectric material.The dielectric material is typically annealed before the top electrodeis formed.

U.S. Pat. No. 7,101,754 discloses forming mixed dielectric films,composed of a high-k dielectric to produce a certain level ofcapacitance and a relatively lower-k dielectric to control leakagecurrent, on a conductor material. The dielectric film having acomposition of SiO₂ and TiO₂ made by a sol-gel process is applied onto asubstrate using a spin-on technique. The discontinuous layer is annealedin the presence of a reactive species so that exposed portions of theconductor material are converted to an insulating material. However,forming the mixed dielectric films is difficult due to the, oftentimes,conflicting deposition requirements of the high-k dielectric and therelatively lower-k dielectric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial cross-sectional view of an embodiment of aninsulative element according to the present disclosure.

FIG. 2 shows a partial cross-sectional view of a second embodiment of aninsulative element according to the present disclosure.

FIG. 3 shows a partial cross-sectional view of a third embodiment of aninsulative element according to the present disclosure.

FIG. 4 shows a partial cross-sectional view of an embodiment of acapacitor including an insulative element as in FIG. 1, FIG. 2, or FIG.3.

FIGS. 5A through 5D illustrate an embodiment of a process for forming aninsulative element according to the present disclosure, such as theinsulative element of FIG. 1.

FIGS. 6A through 6E illustrate an embodiment of a process for forming aninsulative element according to the present disclosure, such as theinsulative element of FIG. 2.

FIGS. 7A through 7F illustrate an embodiment of a process for forming aninsulative element according to the present disclosure, such as theinsulative element of FIG. 3.

DETAILED DESCRIPTION

The following description provides specific details, such as materialtypes, material thicknesses, and processing conditions in order toprovide a thorough description of embodiments of the present invention.However, a person of ordinary skill in the art will understand that theembodiments of the present invention may be practiced without employingthese specific details. Indeed, the embodiments of the present inventionmay be practiced in conjunction with conventional fabrication techniquesemployed in the industry.

As used herein, the term “amorphous” means and includes without a realor apparent crystalline form, such as non-crystalline or at leastsubstantially non-crystalline.

As used herein, the term “crystalline” means and includes amonocrystalline or polycrystalline chemical structure or phase. Acrystalline phase may include one or more molecules of another material.

As used herein, terms such as “first” and “second” are used to merelydifferentiate between structures, methods, materials, or othercomponents, and do not necessarily refer to any particular sequence.

As used herein, the term “forming” means and includes any method ofcreating, building, or depositing a material. For example, forming maybe accomplished by atomic layer deposition (ALD), chemical vapordeposition (CVD), sputtering, spin-coating, diffusing, depositing,growing, or any other forming technique known in the art ofsemiconductor fabrication.

As used herein, the term “substantially” means and includes mostly,essentially, fully, or entirely. By way of example, the phrase “asubstantially crystalline material” may refer to a material with aportion in a crystalline state, the portion in the range of from about90% by volume up to and including about 100% by volume of the material,and a remaining portion (i.e., about 10% to about 0% by volume,respectively) in an amorphous state.

As used herein, the term “substrate” refers to any supporting basematerial, structure, or construction. By way of example and notlimitation, a substrate may be a semiconductor substrate, a basesemiconductor layer or structure on a supporting structure, a metal orpolysilicon electrode, or a semiconductor substrate having one or morelayers, structures, or regions formed thereon. In some embodiments, asemiconductor substrate may have at least a portion thereof doped so asto be conductive, such as an n-doped or p-doped silicon substrate.

As used herein, the term “structure” refers to a layer or film, or to anonplanar mass, such as a three-dimensional mass, having a substantiallynonplanar configuration. The term “structure” also may refer to a massformed of more than one layer, film, non-planar mass, or combinationthereof.

Some embodiments of insulative elements including dielectric materialshaving a high dielectric constant (k) and a low leakage current areshown in FIGS. 1 through 4 and are described as follows. Similarstructures or components in the various drawings may retain the same orsimilar numbering for the convenience of the reader; however, thesimilarity in numbering does not mean that the structures or componentsare necessarily identical in size, composition, configuration, or anyother property. The insulative elements include a first dielectricmaterial and a second dielectric material. During fabrication of theinsulative element, the second dielectric material may be formed as acapping material over the first dielectric material and may function asa dopant source for the first dielectric material. Upon exposure toheat, the second dielectric material may form an alloy phase with thefirst dielectric material. In combination, the first dielectric materialand the second dielectric material may form a dielectric material of theinsulative element.

In some embodiments, an insulative element 10, as shown in any of FIGS.1 through 3, may be used as a component of a semiconductor device. Byway of example, the insulative element 10 may be useful as a dielectricmaterial in a capacitor, such as in a planar cell, trench cell, (e.g.,double sidewall trench capacitor), or stacked cell (e.g., crown, V-cell,delta cell, multi-fingered, or cylindrical container stacked capacitor).The insulative element 10 may also be useful as a gate dielectric in atransistor, or as an insulating material between conductive componentsor portions thereof that are to be isolated electrically. While theintended uses of the insulative elements 10 are described herein, anyapplication where high-k dielectric materials may be desirable iscontemplated by the present disclosure. The insulative element 10 may beused in a metal-insulator-metal (MIM) capacitor or ametal-insulator-semiconductor (MIS) capacitor or gate stack. Theinsulative element 10 may provide a high dielectric constant (k) and alow leakage current to a semiconductor device that includes theinsulative element 10.

As shown in FIG. 1, some embodiments of the present disclosure includean insulative element 10 having a high dielectric constant (k) with lowleakage current. The insulative element 10 may include a firstdielectric material 20 and a second dielectric material 22 over asubstrate 24. In some embodiments, the substrate 24 may be or include aconductive material, such as at least one of polysilicon and a metalincluding, but not limited to, platinum, aluminum, iridium, rhodium,ruthenium, titanium, tantalum, tungsten, alloys thereof, andcombinations thereof. If the insulative element 10 is to be used in aMIM capacitor, the substrate 24 may be a metal electrode. If theinsulative element 10 is to be used in a MIS capacitor or gate stack,the substrate 24 may be silicon.

The first dielectric material 20 and the second dielectric material 22may each include at least one metal oxide material, with the firstdielectric material 20 and the second dielectric material 22 includingdifferent metal oxide materials that have different dielectric constants(k). To provide the different dielectric constants (k), the metal oxidematerials of the first dielectric material 20 and the second dielectricmaterial 22 may differ in the elements present therein or in thestoichiometry of the elements present therein. By way of example and notlimitation, the metal oxide material of the first dielectric material 20may include one or more of a hafnium oxide (Hf_(y)O_(x), such as HfO₂),a zirconium oxide (Zr_(y)O_(x), such as ZrO₂), an aluminum oxide(Al_(y)O_(x), such as Al₂O₃), a strontium oxide (Sr_(y)O_(x), such asSrO), a titanium oxide (Ti_(y)O_(x), such as TiO₂), a niobium oxide(Nb_(y)O_(x), such as Nb₂O₅), a tantalum oxide (Ta_(y)O_(x), such asTa₂O₅), and a rare earth oxide, wherein each of x and y is an integergreater than or equal to 1. As used herein, the phrase “rare earthoxide” refers to an oxide of a rare earth element, including theelements scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce),praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm),europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium(Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Thefirst dielectric material 20 may also include one or more of a siliconoxide (Si_(y)O_(x), such as SiO₂), a germanium oxide (Ge_(y)O_(x), suchas GeO₂), and an oxynitride (such as SiO_(x)N_(y) or HfO_(x)N_(y)).

The second dielectric material 22 may include a metal oxide orcombinations of metal oxides different from the first dielectricmaterial 20. The second dielectric material 22 may include one or moreof the metal oxides described above for the first dielectric material20, such as at least one of HfO₂, ZrO₂, Al₂O₃, SrO, TiO₂, Nb₂O₅, Ta₂O₅,and a rare earth oxide. The second dielectric material 22 may alsoinclude one or more of SiO₂, GeO₂, and an oxynitride. The composition ofthe second dielectric material 22 may differ from the composition of thefirst dielectric material 20 in that the second dielectric material 22may include different elements than the first dielectric material 20 or,if the same elements are present, a different stoichiometry of therespective elements. In some embodiments, the second dielectric material22 may include one or more of the same metal oxides as the firstdielectric material 20, in addition to another metal oxide material. Forexample, where the first dielectric material 20 includes primarily HfO₂,the second dielectric material 22 may include HfO₂ in combination withanother metal oxide, such as TiO₂. Therefore, the overall composition ofthe second dielectric material 22 may differ from the overallcomposition of the first dielectric material 20, although somesimilarity in composition may be present.

In some embodiments, the first dielectric material 20 includes one ormore of HfO₂ and ZrO₂ and, optionally, one or more of Al₂O₃ and SiO₂,and the second dielectric material 22 includes one or more of SrO, TiO₂,Nb₂O₅, Ta₂O₅, and the rare earth oxide. For example, the firstdielectric material 20 may include at least one of HfO₂ and ZrO₂ and atleast one of SiO₂ and Al₂O₃, the latter of which, if present, mayaccount for a relatively small proportion of the first dielectricmaterial 20. The second dielectric material 22 may, optionally, alsoinclude one or more of SiO₂, Al₂O₃, ZrO₂, and another material, inaddition to the one or more of SrO, TiO₂, Nb₂O₅, Ta₂O₅, and the rareearth oxide. The first dielectric material 20 may also include at leasta portion (such as the portion closest to the second dielectric material22) within which molecules of the second dielectric material 22 aredispersed. In other words, the portions of the first dielectric material20 may be “doped” with metal oxide molecules of the second dielectricmaterial 22. As used herein, the term “dispersed” means and includeslocated within, and may refer to varying concentrations across a region(i.e., heterogeneous) or may refer to a substantially constantconcentration across a region (i.e., homogeneous). Molecules dispersedin a structure or material may refer to molecules located at variouspositions in the structure or material. For example, dispersed moleculesmay include molecules of the second dielectric material 22 incorporatedinto the crystalline phase of the first dielectric material 20, locatedbetween the grain boundaries of the crystalline phase of the firstdielectric material 20, located in an amorphous portion of the firstdielectric material 20, or combinations thereof.

The metal oxide material of the second dielectric material 22 may beselected to have a dielectric constant (k) higher than the dielectricconstant (k) of the metal oxide material of the first dielectricmaterial 20. For example, if the first dielectric material 20 includesprimarily HfO₂, which has a dielectric constant (k) of about 25, thesecond dielectric material 22 may include primarily Nb₂O₅, which has adielectric constant (k) of about 41. However, the selection of metaloxide materials of the first and second dielectric materials 20, 22 maybe altered such that the metal oxide material of the second dielectricmaterial 22 has a dielectric constant (k) lower than the dielectricconstant (k) of the metal oxide material of the first dielectricmaterial 20. The difference in dielectric constant (k) between the firstand second dielectric materials 20, 22 may be less than about 5.

In some embodiments, a material forming a majority of a region ormaterial may be referred to as a matrix, and a material forming asmaller portion of the region may be referred to as a dopant. The matrixmay have the dopant(s) dispersed therein. By way of example, the firstdielectric material may function as the matrix while the metal oxide ofthe second dielectric material may function as the dopant(s).

In some embodiments, there may be no clear interface or boundary betweenthe first dielectric material 20 and the second dielectric material 22.For example, some regions of the first dielectric material 20 mayexhibit a relatively higher concentration of metal oxide molecules fromthe second dielectric material 22 and other regions of the firstdielectric material 20 may exhibit a relatively lower concentration ofmetal oxide molecules from the second dielectric material 22. However,for convenience and clarity, the first and second dielectric materials20, 22 are illustrated herein as having a distinct interface betweenadjacent materials.

The first dielectric material 20 may be formed at a greater thicknessthan the second dielectric material 22. For example, the firstdielectric material 20 may have a thickness of between about 30Angstroms (Å) and about 80 Å, and the second dielectric material 22 mayhave a thickness of between about 5 Å and about 30 Å. The seconddielectric material 22 may be sufficiently thin such that itscontribution to the total thickness of the dielectric material 14 (thefirst dielectric material 20 and the second dielectric material 22, seeFIG. 4) is minimal compared to its contribution to the dielectricconstant of the first dielectric material 20 and the second dielectricmaterial 22. Depending on the intended use of the insulative element 10,one or both of the first and second dielectric materials 20, 22 may bethicker or thinner than the ranges recited.

The first dielectric material 20 of the insulative element 10 may besubstantially crystalline, although some portions of the firstdielectric material 20 may be amorphous. In some embodiments, the seconddielectric material 22 may be substantially crystalline. However, inother embodiments, the second dielectric material may be substantiallyamorphous. In some embodiments, at least a portion of the metal oxidesof the second dielectric material 22 may be distributed in the firstdielectric material 20. In other words, at least some of the metal oxidemolecules of the second dielectric material 22 may be incorporated intoor distributed within or between the lattice or crystalline phase of thefirst dielectric material 20. As described in more detail below,molecules of the metal oxide of the second dielectric material 22 maydiffuse into the first dielectric material 20, doping the firstdielectric material 20 with the metal oxide of the second dielectricmaterial 22. A crystalline dielectric material generally has a higherdielectric constant (k) compared to the same dielectric material in anamorphous phase or state. Thus, the dielectric constant (k) of theinsulative element 10 may be tailored by crystallizing none, some,portions of, or substantially all of the first and second dielectricmaterials 20, 22, for example.

The crystalline phase of one or both of the first and second dielectricmaterials 20, 22 may be achieved by annealing one or both of the metaloxide materials of the first and second dielectric materials 20, 22.Additionally, the dispersion of molecules of the second dielectricmaterial 22 within the first dielectric material 20 (also referred to as“doping” of the first dielectric material 20) may be accomplished byannealing the metal oxide material of the first and second dielectricmaterials 20, 22. As used herein, “annealing” refers to subjecting toelevated temperatures, or heating, for a period of time. A more detaileddescription of annealing and crystallizing the metal oxide materials isprovided below. Annealing one or both of the metal oxide materials ofthe first and second dielectric materials 20, 22 may provide theinsulative element 10 having the higher k compared to a so-called “mixeddielectric” in which a material including a mixture of two dielectricmaterials is formed and then annealed.

Referring now to FIG. 2, in some embodiments, one or more additionalmaterials may be present as a part of the insulative element 10. Forexample, an additional dielectric material 26 may be located between thefirst dielectric material 20 and the second dielectric material 22. Theadditional dielectric material 26 may function as a barrier material,preventing or reducing the diffusion and dispersion of molecules of thesecond dielectric material 22 across the additional dielectric material26.

In some embodiments, the insulative element 10 may include theadditional dielectric material 26 located over the second dielectricmaterial 22 (i.e., on the side of the second dielectric material 22opposite the first dielectric material 20, shown by dashed lines in FIG.2 as additional dielectric material 26 a) or located between thesubstrate 24 and the first dielectric material 20 (shown by dashed linesin FIG. 2 as additional dielectric material 26 b), rather than or inaddition to between the first and second dielectric materials 20, 22.The additional dielectric material 26 may modulate diffusion of thesecond dielectric material 22 into the first dielectric material 20.

The additional dielectric material 26 may include one or more of HfO₂,SiO₂, ZrO₂, Al₂O₃, GeO₂, and a rare earth oxide. The additionaldielectric material 26 may have a different composition than the firstdielectric material 20, the second dielectric material 22, or both thefirst and second dielectric materials 20, 22. In some embodiments, theadditional dielectric material 26 may include one or more similar metaloxides to the metal oxide(s) of the first, second, or first and seconddielectric materials 20, 22. By way of example and not limitation, in anembodiment where the first dielectric material 20 includes primarilyHfO₂ and the second dielectric material 22 includes primarily TiO₂, theadditional dielectric material 26 may include primarily SiO₂ or Al₂O₃.The overall composition of the additional dielectric material 26 maydiffer from the overall composition of one or both of the first andsecond dielectric materials 20, 22, although some similarity incomposition may occur.

The additional dielectric material 26 may, in some embodiments, have athickness that is less than a thickness of the first dielectric material20. In some embodiments, the additional dielectric material 26 may havea thickness that is less than both a thickness of the first dielectricmaterial 20 and a thickness of the second dielectric material 22. By wayof example and not limitation, the dielectric material 26 may have athickness in the range of from about one monolayer to about 5 Å.

In some embodiments, the thickness of the additional dielectric material26 may not be clearly defined due to diffusion of the additionaldielectric material 26 into one or both of the first dielectric material20 and the second dielectric material 22. In some embodiments, the firstdielectric material 20 may include at least portions (such as thoseclosest to the second dielectric material 22) wherein molecules of themetal oxides of the second dielectric material 22 are dispersed. Inother words, the portions of the first dielectric material 20 may be“doped” with molecules of the second dielectric material 22.

Referring now to FIG. 3, in some embodiments, the first dielectricmaterial 20 may have a first region 33 being at least substantially freeof molecules of the metal oxide material of the second dielectricmaterial 22, and a second region 34 including molecules of the seconddielectric material 22 dispersed therein. A majority by volume of thefirst region 33 and a majority by volume of the second region 34 of thefirst dielectric material 20 may include the same dielectric material,although the second region 34 may additionally include a higherconcentration of molecules of the second dielectric material 22dispersed therein than the first region 33. In some embodiments, thefirst region 33 and the second region 34 may each be substantiallycrystalline. In some embodiments, the first region 33, the second region34, and the second dielectric material 22 may each be substantiallycrystalline.

While embodiments of the insulative element 10 have been described andillustrated with the first and second dielectric materials 20, 22 havingspecific compositions and shown to be in specific configurations, it isto be understood that these descriptions may be altered. For example, amaterial with a composition similar or identical to the seconddielectric material 22 may be formed on a substrate 24 first, and amaterial with a composition similar or identical to the first dielectricmaterial 20 may be formed over the second dielectric material 22. Insome embodiments, overall properties (e.g., dielectric constant,capacitance, leakage current) of the insulative element 10 may bechanged or tailored by altering the configuration of the firstdielectric material 20 and the second dielectric material 22.

Referring now to FIG. 4, some embodiments of the invention include asemiconductor device structure 30 including a first electrode 12, asecond electrode 16, and dielectric material 14, at least portions ofwhich are located between the first electrode 12 and the secondelectrode 16. The first electrode 12, dielectric material 14, and secondelectrode 16 may be collectively referred to as a capacitor 18.

The first electrode 12 may be a conductive element, which may include,for example, one or more of polysilicon and a metal, including, but notlimited to, platinum, aluminum, iridium, rhodium, ruthenium, titanium,tantalum, tungsten, alloys thereof, and combinations thereof. Thedielectric material 14 may be formed over the first electrode 12. Thesecond electrode 16 may also be a conductive element, which may likewiseinclude, for example, one or more of polysilicon and a metal, including,but not limited to, platinum, aluminum, iridium, rhodium, ruthenium,titanium, tantalum, tungsten, alloys thereof, and combinations thereof.

The dielectric material 14 may include one of the insulative elements 10illustrated and described in reference to FIGS. 1 through 3 above and,therefore, may include first and second dielectric materials 20 and 22,which may, by way of example, have a composition as described withreference to any of FIGS. 1 through 3 above or variations andequivalents thereof. For example, the dielectric material 14 may includethe first dielectric material 20 and the second dielectric material 22.The first dielectric material 20 may be at least substantiallycrystallized and have a first dielectric constant. The first dielectricmaterial 20 may be at least partially doped with the second dielectric22 material having a second dielectric constant.

Some embodiments of methods of forming insulative elements 10 or asemiconductor device structure 30, such as those shown in FIGS. 1through 4, are shown in FIGS. 5A through 7F and are described asfollows. First and second oxide materials 29, 32 may be formed over asubstrate 24 and the first and second oxide materials 29, 32 annealed tomodulate the interaction between the matrix of the first oxide material29 and the dopant of the second oxide material 32. The first and seconddielectric materials 20, 22 may be formed in this manner. The timing ofthe anneal in the process flow may determine whether dopantinterdiffusion is promoted or inhibited. The timing of the anneal in theprocess flow may provide the semiconductor device structure 30 havingincreased k through enhanced diffusion of the dopant or decreased k byhindering the diffusion of the dopant.

One embodiment of a method showing the formation of an insulativeelement 10 (as shown in FIG. 1, for example) or a capacitor is shown inFIGS. 5A through 5D. A first metal oxide material 29 may be formed on asubstrate 24, as shown in FIG. 5A. By way of example and not limitation,the substrate 24 may be or include a capacitor electrode, a portion of atransistor, a semiconductive film, a doped portion of a semiconductormaterial, any other structure whereon a metal oxide material may beformed, or any combination thereof. The first metal oxide material 29may be substantially amorphous at formation. In some embodiments,certain formation techniques, such as CVD, may produce sufficient heatto cause the crystallization of one or more portions of the first metaloxide material 29 upon formation. However, at least a portion of thefirst metal oxide material 29 may remain amorphous during the formationthereof.

By way of example and not limitation, the first metal oxide material 29may be formed to a thickness sufficiently thin to enable small featuresizes of an integrated circuit to be formed and to enable highcapacitance (which is inversely related to the distance from oneelectrode to another, i.e., the thickness of the dielectric material 14,see FIG. 4). At the same time, the first metal oxide material 29 may beformed to be of sufficient thickness to reduce defects and undesirableproperties, such as leakage current, in the semiconductor devicestructure 30. By way of example and not limitation, the first metaloxide material 29, as formed, may have a thickness in the range of fromabout 30 Å to about 80 Å.

The first metal oxide material 29 may be formed from at least one ormore of HfO₂, ZrO₂, Al₂O₃, SrO, TiO₂, Nb₂O₅, Ta₂O₅, and a rare earthoxide. The first metal oxide material 29 may also be formed to includeone or more of SiO₂, GeO₂, and an oxynitride. By way of example and notlimitation, the first metal oxide material 29 may be formed from one ormore of HfO₂ and ZrO₂ and, optionally, one or more of Al₂O₃, and SiO₂.

A second metal oxide material 32 may be formed over the first metaloxide material 29 or portions thereof. The second metal oxide material32 may be formed from a material(s) selected to have a differentdielectric constant (k) than the first metal oxide material 29. Forexample, the second metal oxide material 32 may be a material(s)selected to have a higher dielectric constant (k) than the first metaloxide material 29. In some embodiments, at least a substantial portionof the second metal oxide material 32 may be a material with a higherdielectric constant than the first metal oxide material 29. By way ofexample, the second metal oxide material 32 may be formed from one ormore of SrO, TiO₂, Nb₂O₅, Ta₂O₅, and a rare earth oxide when the firstmetal oxide material 29 is formed from one or more of HfO₂, ZrO₂, SiO₂,and Al₂O₃. Optionally, the second metal oxide material 32 may alsoinclude a material(s) having a relatively lower dielectric constant (k),such as, for example, one or more of SiO₂, Al₂O₃, ZrO₂, and HfO₂.

The second metal oxide material 32 may be formed to be at leastsubstantially amorphous at formation. In some embodiments, certainformation techniques, such as CVD, may produce sufficient heat to causethe crystallization of some of the second metal oxide material 32 atformation. However, at least a portion of the second dielectric material22 may remain amorphous during the formation thereof.

The second metal oxide material 32 may be formed to be sufficiently thinto limit its contribution to the total thickness of the dielectricmaterial 14. However, the second metal oxide material 32 may havesufficient thickness to provide a doping effect on the first metal oxidematerial 29. The doping may occur when molecules of the second metaloxide material 32 diffuse or migrate into the first metal oxide material29. In other words, the second metal oxide material 32 may be formed ata sufficient thickness to provide an effective amount of material todope the first metal oxide material 29 to tailor the properties (e.g.,dielectric constant (k) and leakage current) of the overall insulativeelement 10 or semiconductor device structure 30. The second metal oxidematerial 32 may have a thickness that is the same or different than thethickness of the first metal oxide material 29. In some embodiments, thethickness of the second metal oxide material 32 may be less than thethickness of the first metal oxide material 29. By way of example andnot limitation, the second metal oxide material 32 may have a thickness,as formed, in the range of from about 5 Å to about 30 Å.

In one embodiment, the first metal oxide material 29 is Zr_(y)O_(x) andthe second metal oxide material 32 is a mixture of Zr_(y)O_(x) andNb_(y)O_(x). In one embodiment, the first metal oxide material 29 isZr_(y)O_(x) and the second metal oxide material 32 is a mixture ofSr_(y)O_(x) and Nb_(y)O_(x). In one embodiment, the first metal oxidematerial 29 is Zr_(y)O_(x) and the second dielectric material 22 is amixture of Sr_(y)O_(x), Nb_(y)O_(x), and Ti_(y)O_(x). In one embodiment,the first metal oxide material 29 is Zr_(y)O_(x), the second dielectricmaterial 32 is a mixture of Ti_(y)O_(x) and SiO_(x), and the additionaldielectric material 26 is Al_(y)O_(x).

In some embodiments, the first and second metal oxide materials 29, 32may be heated, as shown by arrows 40 in FIG. 5C. Heating (i.e.,annealing) may cause at least some crystallization of the first metaloxide material 29, producing first dielectric material 20. The annealingmay also cause or induce the migration or diffusion of at least some ofthe metal oxides of the second metal oxide material 32 into the firstmetal oxide material 29. In other words, the first metal oxide material29 may become at least partially doped with molecules of the secondmetal oxide material 32 through the annealing. The first and secondmetal oxide materials 29, 32 are denoted in FIGS. 5C and 5D as first andsecond dielectric materials 20, 22 to indicate that the materials havebeen annealed. The interface between the first and second dielectricmaterials 20, 22 may not be as distinct or clear as is illustrated inFIG. 5C. For example, in some embodiments, the interface may moreaccurately be represented by a gradient of varying concentration ofmetal oxides of the second dielectric material 22 in the firstdielectric material 20. In some embodiments, substantially all of thesecond dielectric material 22 may be incorporated into the firstdielectric material 20 by way of diffusion.

In some embodiments, annealing may also cause at least somecrystallization of the second metal oxide material 32. The temperatureused to anneal and crystallize a dielectric material may depend on thecomposition of the dielectric material. The amount of time to which thefirst and second metal oxide materials 29, 32 are exposed to heat maydepend on the anneal temperature. At a relatively high annealtemperature, the amount of time to induce crystallization may be lessthan the amount of time to induce crystallization at a relatively lowertemperature. The anneal temperature and anneal time may be chosen totailor the level of crystallization of at least portions of at least oneof the first and second dielectric materials 20, 22. The annealtemperature and anneal time may also be selected to tailor the amount ofdopant diffusion between the first and second dielectric materials 20,22. By way of example and not limitation, the anneal temperature may bein the range of from about 300° C. to about 700° C., such as from about500° C. to about 700° C., and the anneal time may be in the range offrom about 1 minute to about 60 minutes, such as from about 3 minutes toabout 5 minutes. The anneal may be conducted by increasing thetemperature in a gradient or stepwise manner, or by raising thetemperature to the desired temperature.

Annealing may take place in any atmosphere, depending on the desiredproperties of the first and second dielectric materials 20, 22 for theirintended use. For example, annealing may take place in an inert (e.g.,non-reactive) atmosphere, such as N₂, Ar, or He, in an oxidizingatmosphere, or in a reducing atmosphere.

Optionally, the first metal oxide material 29 may be annealed and atleast partially crystallized before the second metal oxide material 32is formed thereon (not shown). After the second metal oxide material 32is formed, the first and second metal oxide materials 29, 32 may beannealed again. This process may result in an insulative element 10including first and second dielectric materials 20, 22 having aneffective dielectric constant that is lower than an effective dielectricconstant resulting from a process in which the anneal andcrystallization of the first metal oxide material 29 is not conductedbefore the foimation of the second metal oxide material 32. Withoutbeing bound to a particular theory, it is believed that molecules fromthe second metal oxide material 32 diffuse more readily into an at leastpartially amorphous first metal oxide material 29 than into an at leastpartially crystallized first metal oxide material 29. The amount ofdiffusion between the first and second metal oxide materials 29, 32 mayaffect the overall dielectric constant of an insulative element 10 thatincludes the first and second dielectric materials 20, 22.

In some embodiments, the crystallization of at least portions of one ormore of the first metal oxide material 29 and the second metal oxidematerial 32 may be induced through process acts involving heat thatoccur after forming the first and second metal oxide materials 29, 32,and not by a separate anneal act as described with reference to FIG. 5C.Additionally, the dispersion of molecules (also referred to as “doping”)from the second metal oxide material 32 into the first metal oxidematerial 29 may be accomplished through process acts involving heat thatoccur after forming the first and second metal oxide materials 29, 32,and not by a separate anneal act as described with reference to FIG. 5C.For example, the first and second metal oxide materials 29, 32 may atleast partially include one or more amorphous regions at formation.After formation of the first and second metal oxide materials 29, 32over the substrate 24, one or more further processing acts, such as abackend process, may occur that subject the first and second metal oxidematerials 29, 32 to heat for a desired period of time. By way ofexample, later deposition, diffusion, or anneal acts involved in formingor modifying one or more other structures (such as, for example, anelectrode, a capping layer, contacts, or insulating layers) of thesemiconductor device structure 30 may produce sufficient heat tocrystallize one or more portions of the first and second dielectricmetal oxide materials 29, 32, thus promoting dispersion of moleculesfrom the second metal oxide material 32 into the first dielectric metaloxide material 29 (i.e., doping). In such embodiments, a separate annealact (as described with reference to FIG. 5C) may not be utilized toachieve the crystallization and doping that may be desired in a specificapplication.

Referring now to FIG. 5D, optionally, one or more additional materials38 may be formed over the second dielectric material 22. For example, inembodiments where the first and second dielectric materials 20, 22 areused as a capacitor dielectric (e.g., as the dielectric material 14shown in FIG. 4), the substrate 24 may be or include a first electrodeand the one or more additional materials 38 may be or include a secondelectrode. The second electrode may be formed by conventionalsemiconductor fabrication techniques, which are not described in detailherein.

By way of another example, in embodiments where the first and seconddielectric materials 20, 22 are used as a gate dielectric in a volatiletransistor (not shown), the substrate 24 may be a semiconductorsubstrate and the one or more additional materials 38 may be anelectrically conductive gate structure. The conductive gate structuremay be formed by conventional semiconductor fabrication techniques,which are not described in detail herein. By way of yet another example,in embodiments where the first and second dielectric materials 20, 22are used as a dielectric structure in a non-volatile transistor (notshown), the substrate 24 may be a conductive charge retaining materialand the one or more additional materials 38 may be a conductive controlgate material. The conductive control gate material may be formed byconventional semiconductor fabrication techniques, which are notdescribed in detail herein.

Another embodiment of a method of forming an insulative element 10 (asshown in FIG. 2, for example) or a capacitor is shown in FIGS. 6Athrough 6E.

A first metal oxide material 29 may be formed on a substrate 24, asshown in FIG. 6A and as described above in relation to FIG. 5A. Anadditional oxide material 27 may be formed over the first metal oxidematerial 29, as shown in FIG. 6B. In some embodiments, the additionaloxide material 27 may be a thin layer (relative to the thickness of thefirst metal oxide material 29) of material having a different dielectricconstant than the first metal oxide material 29. For example, theadditional oxide material 27 may be formed to have a thickness in therange of about one monolayer to about 5 Å at formation.

The additional oxide material 27 may function as a diffusion barrier toreduce, control, or eliminate diffusion or migration of dopants acrossthe thickness of the additional oxide material 27 in a subsequentprocess involving heating of the insulative element 10. The additionaloxide material 27 may be formed to include, by way of example, one ormore of HfO₂, SiO₂, Al₂O₃, GeO₂, an oxynitride, and a rare earth oxide.For example, the additional oxide material 27 may be or include a metaloxide material.

A second metal oxide material 32 may be formed over the additional oxidematerial 27, as shown in FIG. 6C and as explained above with referenceto FIG. 5B. The second metal oxide material 32 may be selected to have adifferent dielectric constant than the first metal oxide 29 and theadditional oxide material 27. For example, the second metal oxidematerial 32 may have a higher dielectric constant than the first metaloxide material 29.

The first metal oxide material 29, second metal oxide material 32, andadditional oxide material 27 may be annealed to induce one or more ofcrystallization and diffusion, as shown by arrows 40 in FIG. 6D. Withoutbeing bound to a particular theory, the presence of the additional oxidematerial 27 between the first and second metal oxide materials 29, 32may substantially reduce, control, or eliminate diffusion (e.g., doping)of the first metal oxide material 29 with molecules of the second metaloxide material 32 during the annealing process. However, the anneal maycause molecules from the additional oxide material 27 to diffuse into atleast one of the first metal oxide material 29 and the second metaloxide material 32. One or more of the first metal oxide material 29,second metal oxide material 32, and additional oxide material 27 may beat least partially crystallized by the annealing. For example,substantially all of the first metal oxide material 29 may becrystallized by the annealing.

Optionally, the annealing may not occur at this point in the process.Instead, the annealing may occur during a subsequent process act, suchas by heating from a backend process. By way of example and notlimitation, any other subsequent deposition, diffusion, or anneal actsin conjunction with forming the semiconductor device structure 30incorporating an insulative element 10 formed by this method may providesufficient heat to crystallize at least a portion of the first metaloxide material 29. The heat from the backend process may also inducediffusion of dopants between the additional oxide material 27 and atleast one of the first metal oxide material 29 and the second metaloxide material 32.

The annealing or heating from a backend process may inducecrystallization and doping of one or more of the first metal oxidematerial 29, second metal oxide material 32, and additional oxidematerial 27, resulting in an insulative element including a firstdielectric material 20, a second dielectric material 22, and anadditional dielectric material 26, as illustrated in FIG. 6D.

Optionally, one or more additional materials 38 may be formed over thesecond dielectric material 22, as shown in FIG. 6E and as explainedabove with reference to FIG. 5C. For example, the dielectric materialformed by this method may function as a capacitor dielectric, and thesubstrate 24 may be or include a first electrode and the one or moreadditional materials 38 may be or include a second electrode. The secondelectrode may be formed by conventional semiconductor fabricationtechniques, which are not described in detail herein.

The method described with reference to FIGS. 6A through 6E may, in someembodiments of the invention, be altered by forming the additionaldielectric material 26 at a different location. For example, theadditional dielectric material 26 may be formed before the first metaloxide material 29 (i.e., the additional dielectric material 26 may belocated between the substrate 24 and the first dielectric material 20)(not shown). By way of another example, the additional dielectricmaterial 26 may be formed after the second metal oxide material 32(i.e., the additional dielectric material 26 may be located between thesecond dielectric material 22 and the one or more additional materials38) (not shown). In some embodiments, more than one additionaldielectric material 26 may be formed, and multiple locations in thedielectric structure may have an additional dielectric material 26. Eachvariation in location of the one or more additional dielectric materials26 may change the properties (e.g., capacitance, dielectric constant,leakage current) of the insulative element 10 formed by the methodsdescribed. In this manner, the properties of the dielectric structuremay be tailored to the specific application contemplated.

Another embodiment of a method of forming an insulative element 10 (asshown in FIG. 3, for example) or a capacitor is shown in FIGS. 7Athrough 7F.

A first region 35 of a first metal oxide material 29 may be foiined on asubstrate 24, as shown in FIG. 7A and as described above in relation toFIG. 5A. The first region 35 may be at least substantially amorphous atformation. Next, the first region 35 may be annealed to induce at leastsome crystallization of the first region 35 of the first metal oxidematerial 29, as shown by the arrows 42 representing a first anneal inFIG. 7B. This first anneal may result in an at least partiallycrystallized first region 33 of a first dielectric material 20 (see FIG.3). In some embodiments, at least substantially all of the first region33 may be crystallized through the first anneal.

After the first region 33 is annealed and at least partiallycrystallized, a second region 36 of the first metal oxide material 29may be formed over the first region 33, as shown in FIG. 7C. The secondregion 36 may be at least substantially amorphous at formation. Therelative thicknesses of the first region 35 and the second region 36 maybe adjusted to tailor the dielectric constant (k) of the insulativeelement 10.

A second metal oxide material 32 may be formed over the second region36, as shown in FIG. 7D and as explained above with reference to FIG.5B. The second metal oxide material 32 may be selected to have adifferent dielectric constant than the first and second regions 35, 36of the first metal oxide material 29. For example, the second metaloxide material 32 may be selected to have a higher dielectric constantthan the first metal oxide material 29.

The first region 33, the second region 36, and the second metal oxidematerial 32 may be annealed, as shown by arrows 44 representing a secondanneal, to induce one or more of crystallization and diffusion, as shownin FIG. 7E. Without being bound to a particular theory, the initialcrystallization or pre-crystallization of the first region 35 of thefirst metal oxide material 29 (forming an at least partiallycrystallized first region 33) may reduce, control, or eliminate dopingof the first region 33 with molecules from the second metal oxidematerial 32 during the annealing process, while the amorphous state ofthe second region 36 of the first metal oxide material 29 may enable atleast some doping of the second region 36 with molecules of the secondmetal oxide material 32 during the annealing process. By way of exampleand not limitation, this method may result in a first region 33 of afirst dielectric material 20 being at least substantially free ofdopants from the second metal oxide material 32 and a second region 34of a first dielectric material 20 including dopants from the secondmetal oxide material 32 dispersed therein (see FIGS. 7E and 7F).

Optionally, one or more additional materials 38 may be formed over thesecond dielectric material 22, as shown in FIG. 7F and as explainedabove with reference to FIG. 5C. In embodiments where this method isused to form a capacitor, the substrate 24 may be or include a firstelectrode and the one or more additional materials 38 may be or includea second electrode. The second electrode may be formed by conventionalsemiconductor fabrication techniques, which are not described in detailherein.

The method described with reference to FIGS. 7A through 7F may, in someembodiments of the invention, be altered by omitting the second annealrepresented by arrows 44 in FIG. 7E and replacing it with heat producedby a backend process. For example, any other subsequent deposition,diffusion, or anneal in conjunction with forming an integrated circuitincorporating an insulative element 10 formed by this method may providesufficient heat to crystallize at least a portion of the second region36 and to induce diffusion of at least some dopants from the secondmetal oxide material 32 into the second region 36, forming an at leastpartially crystallized and doped second region 34 of the firstdielectric material 20. In this manner, the heat sufficient tocrystallize at least a portion of the second region 34 and to inducediffusion of at least some dopants from the second metal oxide material32 into the second region 34 may be provided by a backend process ratherthan by a separate anneal act (as shown in FIG. 7E).

CONCLUSION

In one embodiment, a method of forming an insulative element isdescribed including forming a first metal oxide material on a substrate,forming a second metal oxide material over at least a portion of thefirst metal oxide material, and heating at least one of the first metaloxide material and the second metal oxide material to crystallize atleast a portion thereof.

In a further embodiment, a method of forming an insulative element isdescribed, including forming a substantially crystalline dielectricmaterial on a substrate, forming a metal oxide material having a greaterdielectric constant than the substantially crystalline dielectricmaterial over the substantially crystalline dielectric material, andheating the substantially crystalline dielectric material and the metaloxide material to induce diffusion of dopants from the metal oxidematerial into the substantially crystalline dielectric material.

In an additional embodiment, a method of forming a capacitor isdescribed, including forming a first electrode, forming a dielectricmaterial over and in contact with the first electrode including forminga first oxide and a second oxide, heating at least one of the first andsecond oxides, and forming a second electrode over the dielectricmaterial. The heating of the at least one of the first and second oxidesat least partially crystallizes at least one of the first and secondoxides.

In another embodiment, an insulative element is described, including asubstantially crystalline first dielectric material having a firstdielectric constant on a substrate and a second dielectric materialhaving a second dielectric constant different than the first dielectricconstant positioned over the first dielectric material. The firstdielectric material may include dopants of the second dielectricmaterial dispersed therein. The dielectric structure may also include anadditional dielectric material.

In an additional embodiment, an insulative element is described,including a substrate and a first dielectric material in contact with atleast a portion of the substrate. The first dielectric material mayinclude an at least substantially crystalline metal oxide matrix and ametal oxide dopant dispersed within at least a portion thereof. Themetal oxide matrix may include a first region including the metal oxidedopant dispersed therein and a second region being substantially free ofthe metal oxide dopant.

While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, the invention is not intended to be limited to the particularforms disclosed. Rather, the invention is to cover all modifications,combinations, equivalents, and alternatives falling within the scope ofthe invention as defined by the following appended claims and theirlegal equivalents.

1. A method of forming an insulative element, comprising: forming afirst metal oxide material having a first dielectric constant on asubstrate; forming a second metal oxide material having a seconddielectric constant different from the first dielectric constant over atleast a portion of the first metal oxide material; and heating at leastone of the first metal oxide material and the second metal oxidematerial to crystallize at least a portion of the at least one of thefirst metal oxide material and the second metal oxide material.
 2. Themethod of claim 1, wherein forming a second metal oxide material havinga second dielectric constant different from the first dielectricconstant comprises forming a second metal oxide material having a seconddielectric constant greater than the first dielectric constant.
 3. Themethod of claim 1, wherein heating at least one of the first metal oxidematerial and the second metal oxide material to crystallize at least aportion of the at least one of the first metal oxide material and thesecond metal oxide material comprises crystallizing substantially all ofthe first metal oxide material.
 4. The method of claim 1, furthercomprising forming a dielectric material having a third dielectricconstant different than the first and second dielectric constants incontact with at least one of the first metal oxide material and thesecond metal oxide material.
 5. The method of claim 1, wherein forming afirst metal oxide material having a first dielectric constant on asubstrate comprises forming the first metal oxide material on anelectrode.
 6. The method of claim 1, wherein heating at least one of thefirst metal oxide material and the second metal oxide material comprisesheating the first metal oxide material and the second metal oxidematerial after forming both the first metal oxide material and thesecond metal oxide material.
 7. The method of claim 6, wherein heatingthe first metal oxide material and the second metal oxide material afterforming both the first metal oxide material and the second metal oxidematerial comprises subjecting the first and second metal oxide materialsto heat during at least one deposition or diffusion act occurring afterforming the first and second metal oxide materials.
 8. A method offorming an insulative element, comprising: forming a substantiallycrystalline dielectric material on a substrate; forming a metal oxidematerial having a dielectric constant greater than a dielectric constantof the substantially crystalline dielectric material over thesubstantially crystalline dielectric material; and heating thesubstantially crystalline dielectric material and the metal oxidematerial to induce diffusion of at least some dopants of the metal oxidematerial into the substantially crystalline dielectric material.
 9. Themethod of claim 8, wherein forming a substantially crystallinedielectric material on a substrate comprises: forming a substantiallyamorphous metal oxide material on the substrate; and annealing thesubstantially amorphous metal oxide material to crystallize asubstantial portion of the substantially amorphous metal oxide material.10. The method of claim 9, wherein annealing the substantially amorphousmetal oxide material to crystallize a substantial portion of thesubstantially amorphous metal oxide comprises annealing thesubstantially amorphous metal oxide material at a temperature of fromabout 300° C. to about 700° C.
 11. The method of claim 8, whereinforming a substantially crystalline dielectric material comprisesforming the substantially crystalline dielectric material having athickness in the range of from about 30 Å to about 80 Å.
 12. The methodof claim 8, wherein forming a metal oxide material having a dielectricconstant greater than a dielectric constant of the substantiallycrystalline dielectric material over the substantially crystallinedielectric material comprises forming the metal oxide material having athickness of from about 5 Å to about 30 Å.
 13. The method of claim 12,further comprising forming another oxide material at least partiallybetween the substantially crystalline dielectric material and the metaloxide material, the another oxide material having a compositiondifferent than each of the substantially crystalline dielectric materialand the metal oxide material.
 14. The method of claim 13, whereinforming another oxide material comprises forming another oxide materialhaving a thickness of from about 1 monolayer to about 5 Å.
 15. A methodof forming a capacitor, comprising: forming a first electrode; forming adielectric material over and in contact with the first electrode,comprising: forming a first oxide having a first dielectric constant;forming a second oxide having a second dielectric constant greater thanthe first dielectric constant over the first oxide; heating at least oneof the first oxide and the second oxide to at least partiallycrystallize at least one of the first oxide and the second oxide; andforming a second electrode over the dielectric material.
 16. The methodof claim 15, wherein forming a first oxide having a first dielectricconstant comprises: forming a first portion of the first oxide in anamorphous state; annealing the first portion of the first oxide tocrystallize substantially all of the first portion of the first oxide;and forming a second portion of the first oxide in an amorphous stateover the annealed first portion of the first oxide.
 17. The method ofclaim 16, further comprising diffusing dopants of the second oxide intothe crystallized first portion of the first oxide.
 18. The method ofclaim 1, wherein heating at least one of the first metal oxide materialand the second metal oxide material to crystallize at least a portion ofthe at least one of the first metal oxide material and the second metaloxide material comprises heating the first metal oxide material tocrystallize at least a portion of the first metal oxide material. 19.The method of claim 18, further comprising dispersing dopants of thesecond metal oxide material in the crystallized at least a portion ofthe first metal oxide material.
 20. The method of claim 19, furthercomprising forming a dielectric material having a material compositiondifferent than the first metal oxide material and the second metal oxidematerial in contact with at least one of the first metal oxide materialand the second metal oxide material.